FILE - This June 9, 2013 file photo provided by The Guardian Newspaper in London shows National Security Agency leaker Edward Snowden, in Hong Kong.

The Guardian/Glenn Greenwald and Laura Poitras/File/AP Photo

WASHINGTON - The remnants of core al Qaeda's battered leadership may still aspire to launch attacks on the United States, but former NSA contract computer specialist Edward Snowden was portrayed today as Public Enemy No. 1 by the country's top intelligence leaders.

Snowden's admitted theft of hundreds of thousands of highly classified files detailing U.S. intelligence collection programs has caused "profound damage," Director of National Intelligence James Clapper said at a Senate committee hearing dedicated to the gravest threats facing the U.S.

"What Snowden has stolen and exposed has gone way, way beyond his professed concerns with so-called domestic surveillance programs," Clapper told the Senate Select Committee on Intelligence in the public hearing. "As a result, we've lost critical foreign intelligence collection sources, including some shared with us by valued partners."

Discussion of Snowden, introduced by Clapper and prolonged by repeated questions from lawmakers, dominated the two-hour hearing and far overshadowed talk of the threats from al Qaeda, Iran, North Korea and other traditional trouble spots.

The 30-year-old former NSA contractor, currently living under temporary asylum in Russia, has been the source of a steady stream of media reports revealing the NSA's vast domestic and international espionage operations, prompting the White House to reconsider, and at least partially reform, its surveillance policy.

Clapper's remarks came at the top of the annual worldwide threat hearing also featuring ominous testimony from the heads of the CIA, FBI, National Counterterrorism Center and Defense Intelligence Agency about heightened concerns over such dangers as that posed by sophisticated hackers employed by Russian and Chinese intelligence services to steal sensitive information.

Even amid dire warnings that gains against core-al Qaeda in Pakistan risk being reversed in the new battlefields of Syria, where estimates of foreign fighters alone top 7,000, and after the U.S. military withdrawal from Afghanistan this year, the greatest condemnation was reserved for the 30-year-old professed "whistleblower" who blew the lid on NSA domestic surveillance.

In rhetoric reminiscent of historic FBI manhunts for Prohibition-era Tommy Gun gangsters or Cold War subversives, Snowden was said to put at risk the lives of countless U.S. spies, intelligence assets and troops in harm's way by the assembled U.S. officials.

"What I do want to speak to as the nation's senior intelligence officer is the profound damage that his disclosures have caused and continue to cause. As a consequence, the nation is less safe and its people less secure," Clapper, a retired Air Force lieutenant general, somberly explained.

He also called on Snowden to return the documents he stole, a cache which Snowden insisted in an interview with German ARD TV this week that he gave to a few select journalists and no longer possesses.

CIA Director John Brennan said his spies have determined that al Qaeda terrorists "are going to school" with each classified document provided to journalists by Snowden. Brennan said they are aiding al Qaeda with "their counter-intelligence program" because all al Qaeda members have to do is "pick up the papers sometimes or do some Google searches for what has been disclosed and leaked."